Cramping and whipped some brownish/pink blood

I’m 12 almost 13 weeks pregnant. I saw the baby at 11 weeks on the ultrasound and heard the heartbeat at the doctors office on Thursday. The past day I’ve felt better less nauseous, tired but I’m getting into the second trimester and I’ve slowly been feeling better. Last night I had light period cramping but shrugged it off as uterus growing. This morning I whipped away blood and I still have the cramping. My doctor doesn’t open till 8:30.. I don’t have enough blood to make it an emergency but I need some sort of reassurance. I’ve spotted throughout the pregnancy but this was different. I’m already fearing the worst, what’s happening doesn’t make sense to me.